Effects of Bacterial Nanocellulose on Properties of Fiber-Cement Composites and Durability to Freeze-Thaw Cycling

In this study, the effect of bacterial nanocellulose, in three levels (control, powder and gel) as a reinforcement for fiber- cement composites was investigated. Also, 6 and 7 wt% of bagasse fibers were used for composite manufacturing. Mechanical and physical properties of composites including modulus of rupture (MOR), modulus of elasticity (MOE), fracture toughness (FT), internal bonding strength (IB), and ware absorption (WA) after 2 and 24h emersion in water were measured. Results showed that composites made with cellulose gel had higher bending strengths, internal bonding strength and fracture toughness. Combination of 7% bagasse fiber content and cellulose gel reduced water absorption of composites. In these composites, internal bonding was increased and less empty spaces remained for water penetration probably due to uniform distribution of fibers and cellulose gel within the cement matrix. XRD analysis showed that peaks corresponding to main hydration products such as CSH and calcium hydroxide had higher intensities in composites containing bacterial cellulose gel. Results obtained from freeze-thaw cycling test showed that composites containing cellulose gel had the higher internal bonding strength compared with other two composites after 20 cycles. In this study, fiber-cement composites produced from 7% bagasse fiber and bacterial cellulose gel have been selected as the optimum treatment.